1. Field of the Invention
The present invention relates to a catalytic hydrogenation treatment process for crude oil and crude oil reformed by the catalytic hydrogenation treatment.
2. Description of the Related Arts
There has heretofore been adopted in an oil refinery industry, a process in which crude oil is distilled into each of fractions, and thereafter each of fractions thus separated is subjected to reforming treatment such as desulfurization. In contrast therewith, there are proposed a process for collectively desulfurizing crude oil as such {refer to Chemical Eng. Progress Vol.67 (8) P.57 (1971)}, a process for collectively desulfurizing the crude oil from which naphtha fraction has been removed {refer to Japanese Patent application Laid-Open No.294390/1991 (Hei-3)} and the like process. According to the above-mentioned process, it is made possible to simplify oil refinery units and besides curtail variable cost of operation, but on the contrary it is made impossible thereby to control in a reactor, the quality per each of the fractions in the oil product. Such control is considered to be extremely difficult from the aspect of its principle.
In addition, the intensified regulation in recent years on the qualities of oil products arising out of the global environmental problems advances at a surprisingly high speed. Such being the case, taking into consideration the prospective regulation on the qualities of the oil products, it has been proved that the foregoing collective desulfurization process not only places a limit on the modification of the qualities of oil products, but also makes the qualities thereof insufficient.
In order to eliminate the disadvantages and defects as mentioned above, there are proposed a process for producing high quality kerosene and gas oil fractions by hydrocracking a heavy oil {refer to Japanese Patent application Laid-Open No. 98270/1994 (Hei-6)} and a method for improving the qualities of kerosene and gas oil fractions by the combination of catalysts for the purpose of hydrogenating treating crude oil or the crude oil from which naphtha fraction has been removed {refer to Japanese Patent application Laid-Open No.268361/1995 (Hei-7), Japanese Patent application Laid--Open No.224890/1992 (Hei-4), Japanese Patent application Laid-Open No.224892/1992 (Hei-4), Japanese Patent application Laid-Open No.27468/1996 (Hei-8), Japanese Patent application Laid-Open No.27469/1996 (Hei-8), etc.}. FIG. 1, FIG. 2, FIG. 3, FIG. 4 and FIG. 5 illustrate the block flow diagrams of the treatment processes.
However, the globally intensified regulation on the qualities of oil products is advancing at unexpectedly high speed as mentioned hereinbefore. For example, in the case of Europe, the sulfur content of gas oil is limited to 500 ppm at the present time, but is required to decrease to 350 ppm in A.D. 2000 and to 50 ppm in A.D. 2005. The polycyclic aromatic series is not limited at the present time, but a proposal of limitation thereof to at most 11% by weight in A.D. 2000 has recently been passed in the European Parliament. These regulations are predicted to spread also through Japan in near future.
There is the possibility of meeting the regulations of up to A.D. 2000 even through the foregoing treatment processes by contriving the combination of operational conditions and catalysts. However it is extremely difficult to cope with the European regulations of A.D. 2005 insofar as the hydrogenation treatment is carried out in the coexistence of a heavy oil.
A general object of the present invention is to provide a process for hydrogenating treating relatively inferior crude oil or the crude oil from which naphtha fraction has been removed without dividing in advance, the crude oil into each of fractions by means of distillation and also to provide reformed crude oil, said process being characterized by its being a hydroreforming process capable of markedly improving the qualities of kerosene and gas oil, fractions and at the same time, controlling the qualities thereof satisfying the prescribed target.
In this connection, it has been found by the present inventors that by subjecting crude oil or the crude oil from which naphtha fraction and the fractions more light than the same (hereinafter referred to as xe2x80x9cNaphtha fractionxe2x80x9d) have been removed (hereinafter referred to as xe2x80x9ctopped crude oilxe2x80x9d) in the presence of a catalyst to consecutive hydrogenation demetalling treatment, hydrocracking treatment and hydrodesulfurization treatment to carry out hydrogenation treatment, subsequently carrying out gas-liquid separation in a gas-liquid separation step, and hydroreforming the resultant gas-phase fluid. The present invention has been accomplished by the above-mentioned findings and information.
Specifically, the gist and outline of the the present invention are as follows.
(1) A process for hydrogenating treating crude oil in the presence of a catalyst which comprises subjecting crude oil to consecutive hydrogenation demetalling treatment, hydrocracking treatment and hydrodesulfurization treatment to carry out hydrogenation treatment, subsequently carrying out gas-liquid separation in a gas-liquid separation step, and hydroreforming the resultant gas-phase fluid.
(2) The process for hydrogenating treating crude oil in the same manner as in the preceding item (1), wherein said crude oil is the topped crude oil from which Naphtha fraction has been removed in a naphtha fraction separation step.
(3) The process for hydrogenating treating crude oil as set forth in the preceding item (2), wherein the Naphtha fraction which has been removed from the crude oil in a naphtha fraction separation step is subjected to hydroreforming together with the gas-phase fluid which has been separated from liquid in the gas-liquid separation step.
(4) The process for hydrogenating treating crude oil as set forth in any of the preceding items (1) to (3), wherein the catalyst used in the hydrocracking treatment is at least one species selected from the group consisting of the metals belonging to group 6, group 8, group 9 and group 10 in the Periodic Table, respectively, and is supported on a carrier composed of 10 to 90% by weight of iron-containing alumino-silicate and 90 to 10% by weight of an inorganic oxide.
(5) The process for hydrogenating treating crude oil as set forth in any of the preceding items (1) to (4), wherein the gas-phase fluid in the course of gas-liquid separation step and the gas-phase fluid after the gas-liquid separation step are subjected to a hydroreforming step at a pressure in the range lower than that in the hydrodesulfurization step by 0 to 50 kg f/cm2 and at a temperature in the range lower than that in said step by 0 to 100xc2x0 C.
(6) Reformed crude oil or reformed topped crude oil which is produced by mixing the liquid-phase fluid formed from the gas-liquid separation step as set forth in any of the preceding items (1) to (5), and the hydrogenatedly reformed gas-phase fluid.
(7) Mixed reformed crude oil which is produced by mixing the topped crude oil which has been reformed in the process as set forth in any of the preceding items (2), (4) and (5), and the Naphtha fraction which has been separated in the naphtha separation step.
(8) Mixed reformed crude oil as set forth in the preceding item (7), which is produced by mixing the Naphtha fraction which has been separated in the naphtha separation step and thereafter hydrodesulfurized, and the topped crude oil which has been reformed.
(9) The process for hydrogenating treating crude oil as set forth in any of the preceding items (1) to (5), wherein part of distillate which is produced by distilling separating any of the reformed crude oil, reformed topped crude oil and the mixed reformed crude oil as set forth in any of the preceding items (6) to (8), is recycled to the hydroreforming step for the gas-phase fluid.